HARTFORD — — Questions about the awarding of city insurance contracts and hundreds of thousands of dollars of missing premium payments became a criminal investigation Friday after FBI agents served a subpoena on the city, ordering it to produce insurance contracts and other materials to a federal grand jury.

Federal authorities also notified the young, Hartford insurance broker at the center of the inquiry, Earl O. O'Garro Jr., that he is a target of the investigation, a source said. O'Garro owns and operates Hybrid Insurance Group.

O'Garro has been unavailable for, or has declined, comment since the insurance controversy became public two weeks ago.

But a report by the Hartford schools department shows that $669,997 in insurance premiums has been unaccounted for since the city finance department wired the money to Hybrid on July 18. The same report said that the missing money makes it appear the city's "standard operating protocols" were violated and that "there may be a conflict of interest" involving City Treasurer Adam Cloud. In early 2012, Cloud transferred a liability policy to O'Garro from another company without, as the report said, the need to compete.

O'Garro, 30, now appears to be in a dire financial position, according to a review of mortgage and other records.

Insurer AmTrust North America has complained to state insurance regulators that Hybrid tried to dupe another company into paying insurance premiums for four purported Connecticut businesses that "exist in name only," according to a complaint by the Connecticut Insurance Department.

After about six months in business, O'Garro was forced to close a restaurant he owned and operated in Middletown and a handful of former employees are pressing him for about $4,000 in back wages. The town of Marlborough, where he lived until recently, is seeking $2,637.28 in overdue automobile taxes.

The financial problems stand in stark contrast to the remarkable access O'Garro appears to have had to substantial sums of money just months ago.

Public records show that O'Garro had access to more than $1.5 million last summer, at about the same time the city wired him more than $800,000, a part of which was to pay the premiums. In addition to the city money, O'Garro obtained three loans in quick succession against one of his homes, a stunning, six-bedroom house on 7 acres in Marlborough. Town records show he apparently paid $539,000 in cash for the house in May 2012.

Fourteen months later, beginning in July 2013, Marlborough land records show, O'Garro took out three mortgages on the house — loans that were worth, collectively, far more than the house. The mortgages were in the amounts of $235,000 on July 9, $530,107.96 on July 24 and $65,000 on August 23.

One of the lenders targeted the house in a foreclosure action on Oct. 15.

Friends and acquaintances are mystified by the events that appear to have overtaken O'Garro.

Friends say he grew up in Windsor but attended private schools, including Avon Old Farms. He graduated from Wesleyan University in Middletown and, in an Internet posting, said he obtained a master's degree in business administration from the University of Hartford.

He registered more than a dozen businesses with the state, many of which apparently existed in name only. He married his wife, Kendra, in a ceremony in Montego Bay, Jamaica in September 2012 and filed for divorce this month.

Hartford Mayor Pedro Segarra on Friday acknowledged that the city had received a subpoena but refused to discuss it. The city's lawyer, Corporation Counsel Saundra Kee Borges, said only that her office will cooperate with investigators.

Hartford city council Minority Leader Larry Deutsch, who has called for an investigation of the missing insurance premium money, said Segarra and Kee Borges also rebuffed his request for information about the missing premium payments.

City officials agreed to release only a cover letter attached to the subpoena. It said the city is required to appear before a grand jury in Hartford or deliver requested records to the FBI.

Even before the FBI announced its interest in the matter, there had been calls for the city's internal audit commission to investigate what some city officials called a possible conflict of interest between Hybrid and Adam Cloud.

In 2012, O'Garro moved his insurance company from Windsor to a building Cloud and others in his family own at 30 Lewis St. in Hartford. O'Garro hired Cloud's brother Christopher, one of the building's owners, as a lobbyist and obtained about $126,000 in state economic develop loans and grants to help pay for the move.

On Wednesday, members of the audit commission said they don't investigate conflicts of interest and recommended that Segarra refer the matter to the city's ethics panel.